Cleaning and Maintenance of Connections.....

I wouldn't use any cleaner/chemicals in an outlet. These are self cleaning. Maybe unplug and plug your component once a month, just a rough guess. It depends on your climate, air leakage through the outlets etc. No cleaner is safer because you don't know if any residue will be left, or contaminant build up you may stir up that is off on the insulator part of the outlet itself. Outlet connections are self cleaning. After unplugging and replugging something back in, look at the plug and you should see a shinny line on the plugs prongs. That is the contact area, and it wiped itself down to the bare clean metal, with no contamination on the connection area. Using any cleaning chemical could leave or stir up something that can turn into a problem. I remember reading an article in Stereophile were he used a Caig cleaner on all of his IC's, and it sounded bad after ward. He had to cleaner the Caig off if memory is correct. I do use Caig myself, but mainly on switch contacts in gear itself. That is a hit or miss fix.Using a cleaner is not a sure thing.

there's a copper cleaning gel containing Hydrofluoric Acid that works miracles.

Hmmm. Its been a long damn time since HS chemistry, but IIRC, hydroflouric acid is extremely corrosive (eats thru glass) and dangerous to handle. I know that you know what you are doing, Albert, but for non chemically savvy 'phile, here is what Wikipedia says:

Water solutions (hydrofluoric acid) are a contact-poison with the potential for deep, initially painless burns, with later tissue death. By interfering with body calcium metabolism, the concentrated acid may also cause systemic toxicity and eventual cardiac arrest and fatality, after contact with as little as 160 cm2 (24.8 square inches) of skin.

. That's about 5" x 5".

As with all things, it's concentration that matters.e

Agreed. With HFl, I would CONCENTRATE real hard on making sure I didn't get any on myself or the metalwork on my gear.

Swamp,

HIFI was suggesting no cleaners of any kind in AC outlets.

Caig Pro Gold is safe for this if someone is wanting to clean an outlet. If it's a concern, avoid it. It's only a suggestion in direct response to the topic at hand.

As for the copper cleaner I agree Hydrofluoric Acid is dangerous, but many products contain it such as rug cleaner (Whink), spray oven cleaner and wheel brightener for automobile mag wheels.

An episode of "Modern Marvels" talked about making soda cans. One of the key steps was a quick dip of the can in Hydrofluoric Acid.

Also, this from the EPA assessment in 1991, a report on safety in the aluminum soda can market:

Present Practice
The reagent used to treat the
surface of the cans contains 2%
to 4% ammonium fluozirconate

Proposed Action

Substitute a nonhazardous reagent that
contains nitric acid and hydrofluoric acid for the hazardous reagent currently used.

If this is acceptable around the food business then my suggestion that careful handling and the concentration levels are the deciding issue. I've used the product for twenty years and I've had no problems. My guess is concentration levels are very low. I have no doubt pure Hydrofluoric Acid is everything you stated.